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* Copyright (C) 2020 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#pragma once
#include <mutex>
#include <binder/IBinder.h>
#include <utils/StrongPointer.h>
namespace android {
namespace media {
// Must be pre-declared, or else there isn't a good way to generate a header
// library.
class ICaptureStateListener;
// A utility for managing capture state change notifications.
// We are making some strong assumptions, for the sake of simplicity:
// - There is no way to explicitly unregister listeners. The only way for a
// listener to unregister is by dying.
// - There's only at most one listener at a given time. Attempting to register
// a second listener will cause a crash.
// - This class isn't really meant to ever be destroyed. We expose a destructor
// because it is convenient to use this class as a global instance or a member
// of another class, but it will crash if destroyed while a listener is
// registered.
// All of these assumptions can be lifted if there is ever a need.
// This class is thread-safe.
class CaptureStateNotifier {
// Ctor.
// Accepts the initial active state.
explicit CaptureStateNotifier(bool initialActive);
// Register a listener to be notified of state changes.
// The current state is returned and from that point on any change will be
// notified of.
bool RegisterListener(const sp<media::ICaptureStateListener>& listener);
// Change the current capture state.
// Active means "actively capturing".
void setCaptureState(bool active);
// Dtor. Do not actually call at runtime. Will cause a crash if a listener
// is registered.
std::mutex mMutex;
sp<media::ICaptureStateListener> mListener;
sp<IBinder::DeathRecipient> mDeathRecipient;
bool mActive;
class DeathRecipient;
void binderDied();
} // namespace android